This invention relates to brushes and particularly to a brush where force of brushing against the surface being brushed is monitored.
The act of brushing necessarily requires the application of some force by the brush against the surface being brushed. The force of the brush against surface must be great enough to accomplish the object of brushing, (e.g., removal of debris from the surface) and yet not be so great as to damage the surface being brushed. Such an application would be, for example, when paint is being scrubbed off painted wood or metal surface in a restoring operation. The requirement is to remove the paint without scratching the surface.
A very common brushing experience is the daily chore of brushing one""s teeth. It has been substantiated that brushing the teeth with excessive force can cause damage to the gums in the form of recession of the gums.
A number of disclosures have appeared which address the problem of preventing application of excessive force when using a toothbrush.
For example, U.S. Pat. No. 2,82,544 to Hadidian discloses a toothbrush in which an array of groups of bristles is supported with the end of each group secured in a flexible band. The groups of bristles are supported in alignment by each group being inserted through a respective hole of an array of holes formed in an extension of the brush handle. Each group slides back and forth in its respective hole in response to varying force of the bristles against the surface being brushed.
U.S. Pat. No. 4,694,844 to Berl et al discloses a toothbrush in which the end of each tuft of an array of tufts (a tuft being group of bristles) is supported by independent resilient members.
U.S. Pat. No. 5,184,368 to Holland discloses an array of tufts supported in the head of the brush wherein the end of each tuft is supported against individual spiral springs.
While each of these devices alleviates the problem of excessive force against the brushed surface (the gums) to some extent, the tufts in each embodiment xe2x80x9cbottom outxe2x80x9d so that the user can still be applying excessive force without realizing it.
It is an object of this invention to provide a brush wherein the user is warned when force of the brush against a surface being brushed exceeds a critical value.
It is another object of the invention that the tufts of bristles be individually positioned with regard to the contour of the surfaces of the teeth.
This invention is directed toward a toothbrush including a plurality of tufts (groups) of bristles mounted in the head of the brush. Each tuft is individually mounted on an elastic diaphragm adjacent a microswitch which is one of an array of microswitches. Each tuft slides back and forth through an aperture of an array of apertures in the head of the toothbrush. When force exceeding a critical value is applied, the tufts will slide to where the end of the tuft will contact and close the adjacent microswitch. When the microswitch closes, an alarm signal generator, encased in the handle with a battery, is activated warning the user that he is exerting excessive force. The alarm signal alerts the user to exert less force to prevent damage to the surface being brushed. The battery, signal generator and microswitches adjacent the ends of the tufts are all enclosed in a housing that is permanently sealed at the time of assembly to prevent access of water to the circuit.
In one embodiment, the alarm is an audio signal generator, e.g., a buzzer or beeper. In another embodiment, the signal is visual, e.g., an LED.